The present invention relates to microstructures, such as reflective micromirrors and micromirror arrays of spatial light modulators used in digital displays systems. A typical micromirror operates in binary states—an ON state and an OFF state. In digital display applications, each micromirror is associated with a pixel of an image. At a time when the pixel is “bright”, a micromirror is set to the “ON” state. Incident light from a light source of the system is reflected by the micromirror in the ON state into a cone of reflected light so as to generate a “bright” pixel on a display target of the system. At another time when the pixel of the image turns to “dark”, the micromirror is switched to the “OFF” state. The incident light is reflected into another cone of reflected light so as to generate a “dark” pixel on the display target.
The ON state and the OFF state of the micromirrors are defined by rotation angles of movable mirror plates of the micromirrors, which have hinges for allowing rotation of the mirror plates. By rotating the mirror plates between the rotation angles, the micromirrors are switched between the ON state and the OFF state, resulting in “bright” and “dark” pixels on the display target. Grayscale images can be produced by the micromirrors using pulse-width-modulation techniques, and color images can be achieved by the micromirrors using sequential-color-display techniques.
Regardless of the different applications, properties, such as mechanical and electrical properties of the structures of the micromirrors are among those determinative factors affecting the performance of the micromirrors in the applications.